This invention relates in general to seal structures and in particular to a combined seal and boot assembly for protectively covering a telescoping connection between two shaft members in a steering shaft assembly.
In virtually every road and off-road vehicle in use today, a steering system is provided for permitting a driver to control the direction of movement. A typical steering system includes a steering wheel, a steering shaft assembly, and a steering device. The steering wheel is rotatably supported within a driver compartment of the vehicle for movement by a driver. The steering shaft assembly is connected to the steering wheel for rotation therewith. The steering device is connected to the steering shaft assembly for turning the wheels of the vehicle in response to rotation of the steering wheel.
In many larger vehicles, such as trucks, the steering shaft assembly is designed not only to provide a rotational driving connection between the steering wheel and the steering device, but further to permit relative axial movement therebetween. Such axial movement has been found to be advantageous for two reasons. First, a relatively small amount of such axial movement is desirable to accommodate vibrations, bumps, and other aspects of normal vehicle operation which would otherwise be transmitted to the steering wheel. Second, when the vehicle is serviced, a relatively large amount of such axial movement is desirable to permit the cab of the vehicle to be pivoted upwardly without requiring disassembly of the steering system.
To accomplish this, it is known to construct the steering shaft assembly from cooperating male and female splined telescoping steering shaft members. The first steering shaft member is connected to the steering wheel by a first universal joint, while the second steering shaft member is connected to the steering device by a second universal joint. The universal joints are provided to permit angular displacement between the steering shaft members and the associated steering wheel and steering device. The splined connection between the first and second steering shaft members provides a rotatable driving connection between the steering wheel and the steering device, while permitting relative axial movement therebetween.
Because the two steering shaft members are usually located in an unprotected area of the vehicle, it is desirable to provide a seal to prevent dirt and other contaminants from entering into the splined connection. In the past, an elastomeric seal was mounted on the female steering shaft member. A portion of the seal extended into engagement with the male steering shaft member for sliding movement thereon. This prior art seal has functioned effectively to prevent dirt and other contaminants from entering into the splined connection. However, it has been found to be undesirable because of the constant sliding movement caused by the relatively small amount of axial movement encountered during normal use, as described above. Such constant sliding movement tends to wear not only the engaging surface of the seal, but also wipes off any lubricant which may be present on the splined male steering shaft member. Thus, it would be desirable to provide a combined seal and boot assembly for protectively covering a telescoping connection between two shaft members in a steering shaft assembly which avoids these problems.